Changes

OSX: Capture 'invalid drawable' message cause by NSOpenGLContext::setView(NULL || incomplete-view) ; Add missing [ctx release] in MyNSOpenGLLayer ; Misc

NSOpenGLContext::setView(NULL || incomplete-view) was called on 2 occasions:
  [1] - MacOSXCGLContext native createContext
  [2] - NSOpenGLLayer internals

For [1], we simply don't call setView(..) ourselfs in case view is NULL or incomplete (invisible)

For [2], we need to wrap the class 'MyNSOpenGLContext:NSOpenGLContext' and capture setView(NULL)

++

Add missing [ctx release] in MyNSOpenGLLayer, otherwise resource won't get dealloc'ed

+++

Misc:
  - MacOSXCGLContext. contextRealized(true): set pbuffer -> ctx, otherwise 1st makeCurrent call will not catch it
  - MacOSXOnscreenCGLContext: don't add ContextUpdater to invisible ProxySurface's (dummy window)

Added very basic unit test of 1 GLProfile initialization